Step 1

In a large mixing bowl, mix together the cold mashed potatoes and the egg. Make sure the egg is evenly distributed through the potatoes.

Step 2

Add the grated onion, flour, salt, and pepper and use a fork to gently mix in the ingredients.

Step 3

Add enough oil to a large fry pan so that it is approximately 1/2" deep and place over medium heat. Allow the oil to come to temperature, about 350°F.

Step 4

Scoop scant 1/2 cups of the potato mixture and gently drop them into the hot oil. Do not overcrowd the pan -- cook no more than 3-4 patties at a time. Gently, flatten each mound into a patty shape with a spatula.

Step 5

Fry for about 2 1/2 to 3 minutes on the first side, until golden brown. Then, slide the spatula under the patty and turn it over. You'll find enlisting a second utensil makes the flip a bit easier! Then, cook for another 2 to 2 1/2 minutes.

Step 6

Transfer the cooked patty to a cooling rack placed over paper towels. Allow to cool slightly, serve, and enjoy!